Decimal to BCD Convertor Keypad

Posted on Dec 4, 2012

When any particular key is pressed, its value will appear in BCD form at the outputs (A, B, C & D). It will remain there until another key is pressed. The 12 keys produce outputs up to `1011`. Extended to 16 keys, the circuit will give the full HEX to BCD conversion.

Decimal to BCD Convertor Keypad
Click here to download the full size of the above Circuit.

The above circuit produces an output ONLY while the input switch is depressed. To make a convertor with a latched output, the following modifications are made. Each CMOS `AND` gate has its free input tied to Vcc, and by the action of R1 through

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